package Backtrace;

/**
 * @author dx
 * @version 1.0
 * @date 2022/6/2 10:30
 * @description: 力扣79
 */
public class Find_Word {
}
class Find_Word_Solution{
    public boolean exit(char[][] board,String word){
        int h = board.length,w = board[0].length;
        boolean[][] visted = new boolean[h][w];
        for(int i = 0;i<h;i++){
            for(int j = 0;j<w;j++){
                boolean flag = check(board,visted,i,j,word,0);
                if(flag){
                    return true;
                }
            }
        }
        return false;
    }
    public boolean check(char[][] board,boolean[][]visted,int i,int j,String s,int k){
        if(board[i][j] != s.charAt(k)){
            return false;
        }else if(k == s.charAt(k)){
            return true;
        }
        visted[i][j] = true;  //回溯选择
        int [][] directions = {{0,1},{0,-1},{1,0},{-1,0}};  //上下左右
        boolean result = false;
        //当前节点上下左右都尝试
        for(int[] dir : directions) {
            int newi = i + dir[0], newj = j + dir[1];
            if (newi >= 0 && newi < board.length && newj >= 0 && newj < board[0].length) {
                if (!visted[newi][newj]) {
                    boolean flag = check(board, visted, newi, newj, s, k + 1);
                    if (flag) {
                        result = true;
                        break;
                    }
                }
            }
        }
        visted[i][j] = false; //回溯剪枝
        return result;
    }
}
/*
class Solution {
    public boolean exist(char[][] board, String word) {
        int h = board.length, w = board[0].length;
        boolean[][] visited = new boolean[h][w];
        for (int i = 0; i < h; i++) {
            for (int j = 0; j < w; j++) {
                boolean flag = check(board, visited, i, j, word, 0);
                if (flag) {
                    return true;
                }
            }
        }
        return false;
    }

    public boolean check(char[][] board, boolean[][] visited, int i, int j, String s, int k) {
        if (board[i][j] != s.charAt(k)) {
            return false;
        } else if (k == s.length() - 1) {
            return true;
        }
        visited[i][j] = true;
        int[][] directions = {{0, 1}, {0, -1}, {1, 0}, {-1, 0}};
        boolean result = false;
        for (int[] dir : directions) {
            int newi = i + dir[0], newj = j + dir[1];
            if (newi >= 0 && newi < board.length && newj >= 0 && newj < board[0].length) {
                if (!visited[newi][newj]) {
                    boolean flag = check(board, visited, newi, newj, s, k + 1);
                    if (flag) {
                        result = true;
                        break;
                    }
                }
            }
        }
        visited[i][j] = false;
        return result;
    }
}




 */